Hello and welcome! If you know nothing about Linux and nothing about mailservers it isn't a good idea to start with a mailserver setup because mailserver setups can get very complicated especially when you don't even understand the os your are wanting to setup your mailserver on. I would start by learning to understand the os you want to use to run your mailserver before attempting to setup a mailserver.
If you choose to not follow that advice anyways no one here is going to write out a step by step guide for you to help you with your setup. If you do want to go that route there are plenty of already written guides about mailserver setups that you can search for on the web but I don't think you would understand those either with your lack of understanding of Linux or mailservers. Choose the way of learning to walk before you attempt to learn to run, so start with a simpler project to help you learn Linux such as installing Linux and learning to work with Linux.
linuxjourney.com
Good luck and enjoy your Linux journey!